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Upper left: Blacksheep touring, monstercross, and gravel grinding freak bike. Sadly, it’s probably seeing the least use of the four right now, so it may eventually go on the auction block if I can’t find a way to give it a little more love. It’s a great bike though–essentially a Rivendell Atlantis in Titanium that will take up to 29er tires. Great for all around fun and mixed surface exploring. S&S coupled too. I may set it up with Jones bars to see if I can’t finally get it in a configuration that I find more comfortable for rougher riding.

Upper right: Pivot dual suspension 29er. Best mountain bike I have ever owned. Love it, and wouldn’t buy another frame even if I had the money. I would like to upgrade the front shock though.

Lower Left: Lugged Kirk all-rounder shod with 35s. Serves mainly as a commuter and dirt road explorer now that I have the Tournesol. My first custom, and one I would never sell. I wouldn’t mind ditching the cantis though. Blech!

Lower Right: the newest addition to the stable, my Tournesol randonneur. Made for long distance road riding and exploring when I want to go long and light. Designed for 28mm tires, it’s the most road like of all my bikes.

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By all accounts, the potato ought to be one of the most fattening natural foods around. It’s glycemic index value is as high as anything, which should spike your blood sugar and trigger an insulin and fat storage response. And yet a guy goes on a two-month potato diet, loses weight and seems to improve health in a couple of other respects too.

To add to that, folks over at the Weston Price Foundation and others have noted that there are traditional cultures around the world that have eaten massive amounts of potato without seeming to suffer from the “diseases of civilization” that plague the developed–and increasingly developing–worlds today.

So how do we reconcile this with the rather simplistic “carbs bad, fat and protein good” thinking that sometimes surfaces in the Paleo and low-carb communities?

One theory is that if (1) you don’t have a metabolism that has already been broken by eating the bags of sugar associated with the Standard American Diet (SAD); and (2) you continue to avoid the junk associated with the SAD, then you can eat decent quantities things like potatoes without weight gain or insanely high blood glucose levels. Those are some pretty big “ifs” for most Americans. It also helps if you are getting regular exercise that depletes muscle glycogen (again, a pretty big “if” for most Americans).

Glucose regulation is quite complex, varying from individual to individual and the overall content of their diet. Ideally, you’d test yourself for glucose intolerance post-meal, as described by Stephan Guyenet here to know what your tolerance level is for potato goodness.

In my own case, I base my potato consumption on activity levels. On weeks when I do a lot of riding, I increase the level of potatoes. On other weeks, such as this one where I’m recovering from a bike crash (and it’s raining anyway), I go fairly low carb. I think I might pick up a glucose meter just out of curiosity. I should add that my diet is otherwise pretty solid (mostly meat, eggs, veggies, and some dairy), and the last thing I need or want to do is lose weight.

Figuring out what works for you takes experimentation and adaptation based on your goals. Even if we start with our best thinking about evolutionary principles, there’s a lot of variation in the traditional diets that have kept people healthy across the world, and there is a lot of learning and study that needs to be done. That’s part of what keeps things interesting.

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The weather report is looking fairly grim these days by SoCal standards, at least from a biking perspective. (Goodness knows we need the water otherwise).

So I finally broke down and mounted up the Honjo fenders my Tounesol was so carefully designed for. It took some futzing as one of the holes Hamco drilled was slightly off center, but all’s well that ends well. I don’t think these guys are going to be coming off soon. They look good, keep you and your bike clean, and don’t weigh that much anyway.

The other new touch is that Ray over at handlebra.com was kind enough to stitch me up a set of burgundy leather bar wrap with baby blue stitching for free. Sweet! It’s a really nice product that wraps easily due to the chamfered edges and, more importantly, has a really nice feel in the hands. Will report back on how it holds up, but I’d expect it to last a while, and since it has no adhesive backing, re-wrapping and re-using will be easy. Thanks Ray!

Next step: a lighter and more minimalist bag for the front. Zugster would probably be just the ticket, if I had some kind of insider connection.

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It’s ironic that I should have to read a blog from New Zealand to realize that an interesting article appeared in today’s LA Times, but such is the nature of the internet. There are quibbles with the LA Time article, but overall it’s great to see that some of this debate is being taken to a wider audience, and to see individuals in mainstream, respected positions (chairman of the department of nutrition at the Harvard School of Public Health) jumping off the anti-fat bandwagon.

Here’s the LA times article with a few items highlighted in bold:

latimes.com

A reversal on carbs

Fat was once the devil. Now more nutritionists are pointing accusingly at sugar and refined grains.

By Marni Jameson, Special to the Los Angeles Times December 20, 2010

Most people can count calories. Many have a clue about where fat lurks in their diets. However, fewer give carbohydrates much thought, or know why they should.

But a growing number of top nutritional scientists blame excessive carbohydrates — not fat — for America’s ills. They say cutting carbohydrates is the key to reversing obesity, heart disease, Type 2 diabetes and hypertension.

“Fat is not the problem,” says Dr. Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health. “If Americans could eliminate sugary beverages, potatoes, white bread, pasta, white rice and sugary snacks, we would wipe out almost all the problems we have with weight and diabetes and other metabolic diseases.”

It’s a confusing message. For years we’ve been fed the line that eating fat would make us fat and lead to chronic illnesses. “Dietary fat used to be public enemy No. 1,” says Dr. Edward Saltzman, associate professor of nutrition and medicine at Tufts University. “Now a growing and convincing body of science is pointing the finger at carbs, especially those containing refined flour and sugar.”

Americans, on average, eat 250 to 300 grams of carbs a day, accounting for about 55% of their caloric intake. The most conservative recommendations say they should eat half that amount. Consumption of carbohydrates has increased over the years with the help of a 30-year-old, government-mandated message to cut fat.

And the nation’s levels of obesity, Type 2 diabetes and heart disease have risen. “The country’s big low-fat message backfired,” says Dr. Frank Hu, professor of nutrition and epidemiology at the Harvard School of Public Health. “The overemphasis on reducing fat caused the consumption of carbohydrates and sugar in our diets to soar. That shift may be linked to the biggest health problems in America today.”

To understand what’s behind the upheaval takes some basic understanding of food and metabolism.

All carbohydrates (a category including sugars) convert to sugar in the blood, and the more refined the carbs are, the quicker the conversion goes. When you eat a glazed doughnut or a serving of mashed potatoes, it turns into blood sugar very quickly. To manage the blood sugar, the pancreas produces insulin, which moves sugar into cells, where it’s stored as fuel in the form of glycogen.

If you have a perfectly healthy metabolism, the system works beautifully, says Dr. Stephen Phinney, a nutritional biochemist and an emeritus professor of UC Davis who has studied carbohydrates for 30 years. “However, over time, as our bodies get tired of processing high loads of carbs, which evolution didn’t prepare us for … how the body responds to insulin can change,” he says.

When cells become more resistant to those insulin instructions, the pancreas needs to make more insulin to push the same amount of glucose into cells. As people become insulin resistant, carbs become a bigger challenge for the body. When the pancreas gets exhausted and can’t produce enough insulin to keep up with the glucose in the blood, diabetes develops.

The first sign of insulin resistance is a condition called metabolic syndrome — a red flag that diabetes, and possibly heart disease, is just around the corner. People are said to have the syndrome when they have three or more of the following: high blood triglycerides (more than 150 mg); high blood pressure (over 135/85); central obesity (a waist circumference in men of more than 40 inches and in women, more than 35 inches); low HDL cholesterol (under 40 in men, under 50 in women); or elevated fasting glucose.

About one-fourth of adults has three or more of these symptoms.

“Put these people on a low-carb diet and they’ll not only lose weight, which always helps these conditions, but their blood levels will improve,” Phinney says. In a 12-week study published in 2008, Phinney and his colleagues put 40 overweight or obese men and women with metabolic syndrome on a 1,500-calorie diet. Half went on a low-fat, high-carb diet. The others went on a low-carb, high-fat diet. The low-fat group consumed 12 grams of saturated fat a day out of a total of 40 grams of fat, while the low-carb group ate 36 grams of saturated fat a day — three times more — out of a total of 100 grams of fat.

Despite all the extra saturated fat the low-carb group was getting, at the end of the 12 weeks, levels of triglycerides (which are risk factors for heart disease) had dropped by 50% in this group. Levels of good HDL cholesterol increased by 15%.

In the low-fat, high-carb group, triglycerides dropped only 20% and there was no change in HDL.

The take-home message from this study and others like it is that — contrary to what many expect — dietary fat intake is not directly related to blood fat. Rather, the amount of carbohydrates in the diet appears to be a potent contributor.

“The good news,” adds Willett, “is that based on what we know, almost everyone can avoid Type 2 diabetes. Avoiding unhealthy carbohydrates is an important part of that solution.” For those who are newly diagnosed, he adds, a low-carb diet can take the load off the pancreas before it gets too damaged and improve the condition — reducing or averting the need for insulin or other diabetes meds.

Americans can also blame high-carb diets for why the population has gotten fatter over the last 30 years, says Phinney, who is co-author of “The New Atkins for a New You” (Simon & Schuster, 2010).

“Carbohydrates are a metabolic bully,” Phinney says. “They cut in front of fat as a fuel source and insist on being burned first. What isn’t burned gets stored as fat, and doesn’t come out of storage as long as carbs are available. And in the average American diet, they always are.”

Here’s how Phinney explains it: When you cut carbs, your body first uses available glycogen as fuel. When that’s gone, the body turns to fat and the pancreas gets a break. Blood sugar stabilizes, insulin levels drop, fat burns. That’s why the diet works for diabetics and for weight loss.

When the body switches to burning fat instead of glycogen, it goes into a process called nutritional ketosis. If a person eats 50 or fewer grams of carbs, his body will go there, Phinney says. (Nutritional ketosis isn’t to be confused with ketoacidosis, a dangerous condition that can occur in diabetics.)

Beyond the fat-burning effects of ketosis, people lose weight on low-carb diets because fat and protein increase satisfaction and reduce appetite. On the flip side, simple carbs cause an insulin surge, which triggers a blood sugar drop, which makes you hungry again.

“At my obesity clinic, my default diet for treating obesity, Type 2 diabetes and metabolic syndrome is a low-carb diet,” says Dr. Eric Westman, director of the Lifestyle Medicine Clinic at Duke University Medical Center, and co-author of the new Atkins book. “If you take carbohydrates away, all these things get better.”

Though the movement to cap carbs is growing, not all nutritional scientists have fully embraced it. Dr. Ronald Krauss, senior scientist at Children’s Hospital Oakland Research Institute and founder and past chair of the American Heart Assn.’s Council on Nutrition, Physical Activity and Metabolism, says that while he fundamentally agrees with those advocating fewer dietary carbs, he doesn’t like to demonize one food group.

That said, he adds, those who eat too many calories tend to overconsume carbohydrates, particularly refined carbohydrates and sugars. “It can be extremely valuable to limit carbohydrate intake and substitute protein and fat. I am glad to see so many people in the medical community getting on board. But in general I don’t recommend extreme dietary measures for promoting health.”

Joanne Slavin, professor of nutrition at the University of Minnesota and a member of the advisory committee for the 2010 Dietary Guidelines for Americans, is less inclined to support the movement. The committee, she says, “looked at carbohydrates and health outcomes and did not find a relationship between carbohydrate intake and increased disease risk.”

Most Americans need to reduce calories and increase activity, Slavin adds. Cutting down on carbs as a calorie source is a good strategy, “but making a hit list of carbohydrate-containing foods is shortsighted and doomed to fail, similar to the low-fat rules that started in the 1980s.”

As nutrition scientists try to find the ideal for the future, others look to history and evolution for answers. One way to put our diet in perspective is to imagine the face of a clock with 24 hours on it. Each hour represents 100,000 years that humans have been on the Earth.

On this clock, the advent of agriculture and refined grains would have appeared at about 11:54 p.m. (23 hours and 54 minutes into the day). Before that, humans were hunters and gatherers, eating animals and plants off the land. Agriculture allowed for the mass production of crops such as wheat and corn, and refineries transformed whole grains into refined flour and created processed sugar.

Some, like Phinney, would argue that we haven’t evolved to adapt to a diet of refined foods and mass agriculture — and that maybe we shouldn’t try.

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There has been some recent discussion in the local mountain bike community as to whether XC weenie types (like me) have any business riding certain trails if they can’t ride the technical features without walking around them. I got a chuckle out of this since many of the gravity oriented riders seem to need to stop to catch their breath at the top of every rise when any climbing is involved, which made me wonder if climbing itself is a “technical feature” that should keep them off certain trails by their own logic.

I’ve got nothing but props for those who can do certain types of downhill riding (so long as they don’t tear up the trail and scare the bejesus out of hikers and equestrians on multi-user trails). I wish I had half the skill of some of these guys. But I do think user conflict on some trials would be somewhat mitigated if all riders had to earn their descent by climbing, forcing them to use a bike that is more than a motorcycle without the motor. In order to contribute to the friendly debate, I made the following warning sign which we might post at the top and bottom of certain XC trails in the area:

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The Paleo Velonaut:

This blog is dedicated to exploring the intersection of cycling, real food, and evolutionary fitness and health principles. Touring, randonneuring, mountain biking, and back country exploring on two wheels, all fueled by the wisdom of our dietary past.